This application is related to copending application Ser. No. 634,970 filed July 27, 1984 for "Strain Gauge Device For Measuring Multi-Component Forces and Torques" which is assigned to the assignee of the present application. That application discloses a multi-component force and torque measurement cell with strain gauges connected to form half-bridge circuits with a constant current source in every bridge branch. The strain gauges are designed and oriented on a measurement spring with defined force introduction for longitudinal and transverse forces and torques in reference to the measurement spring strain directions so that a clearly associated response occurs which can be assigned to the forces and torques. An adequate number of strain gauges is provided so that using the measured voltages which can be picked-off the half-bridge circuits and the standardized tensile effects of the forces and torques impacting on the respective strain gauges, an adequate number of equations can be generated to determine all forces and torques.
The patent application describes a circuit in which a large number of strain gauges wired on one end in parallel by use of a switch and two constant voltage sources can be divided into numerous half bridges. For many applications the measurement results of the half-bridge circuits should be available for processing simultaneously. This cannot be achieved with the known circuit or can only be achieved with another embodiment in which for every bridge arm there is a separate constant current source. Accordingly, it will be appreciated that it would be highly desirable to have the measurement results available for processing simultaneously.
It is an object of the present invention to provide a measurement cell wherein the measurement results are available for processing simultaneously.
It is an object of this invention to provide a circuit which can operate using only two constant current sources and hard-wired circuits without a switch.